The objectives of this research are: division of the process of transcription into discrete chemical steps with measurable parameters; delineation of the extent and nature of the participation of each subunit of the RNA polymerase in each of these steps; identification of active sites formed within, between or among subunits and measurement of $ the effects of alteration of structure of the subunits on each step. The specific aims of this research are: 1) Analyses of temperature sensitive RNA polymerases from Salmonella typhimurium to correlate alteration in function with mutations in specific subunits and to permit definition of biochemical steps in RNA synthesis. 2) Construction of peptide maps of the subunits of E. coli and Salmonella typhimurium RNA polymerases. 3) Correlation of sites involved in specific functions with regions of the peptide map. 4) Characterization of differences between different stable states of RNA polymerase and of RNA polymerase DNA complexes using bivalent crosslinking reagents, cross linking of DNA to RNA polymerase and covalent bonding of RNA polymerase to substrates analogs.